Coating



L. E. POWE R IETHOD OF- APPLYING INSULATOR COATING Sept. 22, 1936.

Original Filed Sept. 29. 1926 v Liz/Pizza 5. Kiwi-v1 Reissued Sept. 22 1936 nrs'r'non or APPLYING INSULATOR COATING Laurence 8. Power, Milwaukee, Wis, assignor,

by mesne admin, to Allen-Bradley Company, Milwaukee. a corporation of Wis- Original application Septeinber 2a, 1920, Serial Divided and application August 28, 192,, Serial No. 388,542- .orlg'lnal No. 1,997,874, April- 16, 1935. Application for rejlle III 2, 193, Serial No. 93,297

4 Claims. (cl. 91-68) This invention relates to certainnew and useful improvements-in apparatus for and method of applying insulator coating and is a division of my application filed September 29, 1926, Serial No.

Heretofore, it has been customary to line houslugs and cabinets for electrical controls by gluing sheet asbestos or other insulating material thereto which has'proven objectionable in that sheet asbestos isnot onlyexpensive but costlytoapplyand fin-thenitsresistancetoanelectricalarcisum satisfactory.

Therefore, this invention contemplata as one of its objects the provision of an improved method of lining cabinets which is comparatively cheap to apply and whereby a very eflicient insulating surface is supplied capable of oifering an excellent resistance to destructive arcing forces.

Another object of this invention resldm in the provision of an improved method of applying a lining surface to-walls which consists in mint neously spraying two solutions to merge just prior toorastheyengagethesurfacetobelined,the solutions having the characteristics of thickening immediately upon contact with each other.

And a'still further object of this invention resides in the provision. of an improved device whereby two solutions may be so applied to a surface as to merge just at or prior to their ensagement therewith.

With the above and other objects in view which will appear as the description proceeds, my inventlon resid in the novel construction, courbination and arrangement of parts submtlally as hereinafter described and more particularly deflned by the appended claims, it being understood thatsudichangesinthepreciseembodlmentof the hereindlsclosedlnv'ention may be made as come within the scope of the claims.

lntheaccompanyingdrawinglhaveillustrated one complete example ofthe physical enrbodiment of my invention constructed according tothebestmodeIhavesofardevised forthe practical application of the principles thereof, and in which:

Figure lisatopplanviewofacompoundair brushorspraydthetype employedincmijunetionwithmyimprovedinsulatorliningandmethe od or applying the sane;

'Flgurezlsaviempartlyinsectionandpartly in elevation, taken through one unit of the compound spray on the plane of the line 2-4 of Fig ure 1, and

Figure 3 is a view taken transversely through Figure 2 on the plane of the line 3-4 and illustrating one of the control valves of a spray unit. The present -conventional manner of insulating the-interior wall surfaces of metal cabinets emplayed in connection with switches and other electric apparatus, is to line the same with asbestos paper. whilethis manner of lining c'abinets has been in vogue for many years and meets with approval by the board of underwriters, it is open to many serious objections such as the inability of asbestos paper to satisfactorily resist an electric arc and also that it is very expensive-to apply, both from the standpoint of material and labor.

This invention, therefore. contemplates the elimination of the cumbersome manner of lining cabinets heretofore used, by the substitution of an improved insulating solution and apparatus for and method of applying the same wherein a better insulating lining is obtained at a considerably reduced cost.

This objectionable type of lining is replaced by one composed of a solution of glue, water and powdered mica applied to the surface and allowed to dry. It has been found from experience that the above solution in the following propor-. tions:

Glue- Water Powdered mica 4 withstand the arc test in a very satisfactory manner. but is open to the objection that when applied to an inclined surface it has a tendency to Parts by weight 3 run, making its application tedious and dimcult 4o 7 Water Glucose m 20 Giycerine 30 Sulphonated nil Glue Water 12 Mica--- 5' Sodium silicate (ordinary commercial grade) 5 The glue and-waterare first mixed, the powdered mica then thoroughly stirred therein and the sodium silicate or water glass added. Immediately upon the addition of the sodium silicate, the viscosity of the solution increases due to the precipitation of colloids, or gel formations. To facilitate the application of the solution to a surface the same is heated to a working temperature preferably under 160 degrees Fahrenheit, at which temperature the same may be applied by means of a brush. Experience has demonstrated that a solution applied as above has the characteristic of remaining where placed on a surface without showing a tendency to run irrespective of the inclination of the surface.

However, a solution having sodium silicate therein is difficult to apply in a'smooth even coating, and this objectionable feature is overcome by spraying the solution in two streams one including glue, water and mica, and the other sodium silicate, the streams preferably coming together just prior to or as they strike the surface to be lined. when applied in this manner, any desired thicknessmay be applied and the solution shows no tendency to run due to the immediate increase in viscosity thereof as the sodium silicate comes into contact with the glue, water and powdered mica.

When the solution is sprayed in divided form the following approximate proportions may be employed:

Parts by weight 7 Glue Water 20 Mice. 5 Sodium silicate 5 The proportion given above may be varied considerably and still produce excellent results. as it is difiicult in actual practice, where the materials are sprayed separately, to maintain the exact proportions between the glue, water and mica, and sodium silicate. It is desirable, however, to avoid a. large excess of sodium silicate over that which is necessary to produce the desired increase in viscosity as sodium silicate is not a good insulator at high temperatures. v

In the accompanying drawing, to which reference is directed, is illustrated the novel spraying apparatus which may be employed to apply my solution, which is preferably divided with the sodium silicate in one container, not shown, and the glue, water and mica in another, not shown.

The spraying apparatus consists of two spray guns or brushes 5 and 6 of complementary construction connected by a plate or bridging member I fixed thereto by screws or other fastenings 8. Asthe spray guns or brushes are identical in construction, the following description refers to but one.

The spray gun consists of a casting 3 having a horizontal barrel It the outer end of which is exthereof.

teriorly threaded, as at H, to adjustably receive a spray nozzle or end cap I2. The spray nozzle is.

provided with a central spray orifice l3 of conical shape at its inner end to cooperate with a jet ll communicating with an air passageway l5 extending throughout the length of the barrel. to one side of a valve 16 mounted in the rear end II The nozzle or end cap I2 has the jet ll projecting into the conical shaped portion of its orifice l3 but spaced therefrom to provide a passage communicating with a chamber l8 from which one or more passages l3 lead to a threaded bore 20 with which'a supply tube 2| leading from the container, not shown, filled with the solution, is connected.

A- handle or grip 22 is fixed to the end ll of the barrel and has .an air supply tube 23 extended therethrough which leads from a source of air under pressure so that operation of the valve l6 by a control knob 24 causes the air to pass through the passage I5 and out through the orifice l3 creating a suction in the chamber l8. The air passes through the orifice iii to produce an injector effect and draws the solution from the container, not shown, through the tube 2| to be expelled through the orifice I 3 in a spray.

The axes of the bores of the orifices l3 of the two spray guns intersect in the manner illustrated in Figure 1 so that the stream or spray 25 of the gun 5 commingles, as at 26, with the stream or spray 21 of the other gun 6,the point of .spring 33 connected with the stem 3| of the valve member. Also connected with the valve stem is I an operating member 32 to which a finger receiving loop 33 is connected to permit the operator to hold the spray gun with the index finger through the loop 33 and the thumb engaging the button 24. Thus, in operation, the operator holds a spray gun in each hand and exerts a pull on the straps 33 and depresses the buttons 24.

- From the foregoing description taken in connection with the accompanying drawing, it will be readily evident to those skiled in the art to which this invention appertains that I provide an improved insulating lining and method of and apparatus for applying the same which very efiiciently and satisfactorily insulates the interior surface of cabinets and the like, and has the ability to successfully withstand destructive arcing forces.

What I claim as my invention is:

1. The hereindescribed method of forming an insulating composition and lining a wall therewith, which consists in simultaneously directing a spray of glue and water solution containing mica in suspension and a spray of a solution of sodium silicate toward each other and on the wall, the solutions commingling to produce a precipitate in the form of a substantially immobile composition llning the wall.

2. The hereindescribed method of, forming-a wall lining composition andlining-a wall therewhich is normally urged closed by a suitable with, which consists in simultaneously sprayin 7| a glue solution and a colloidal solution having the ability to cause a precipitation of colloids in.

the glue solution, onto the wall and toward each other, so that the solutions commingle at or near the wall surface.

3. The hereindescribed method of forming a wall lining composition and lining a wall therewith, which consists in simultaneously spraying onto a wall and toward each other, so that they commingle at or near the wall surface, a solution of sodium silicate and a colloidal solution from which the colloids will be precipitated by the sodium silicate solution.

4. The hereindescribed method of forming an insulating composition and lining a wall therewith, which consists in simultaneously spraying a glue solution and a colloidal solution having the ability to cause a precipitation of colloids in the glue solution, onto the wall and toward each other, so that the solutions commingle at or near the wall surface, one of said solutions containing an inert insulating material.

LAURENCE E. POWER. 

